The present invention relates to a gasket cast within a wall defining an opening for sealing a joint between the wall and an outer surface of an annular member extending through the opening. More particularly, the present invention relates to a gasket cast within a wall defining an opening in a manhole or bell end of a pipe that is folded so as to be protected prior to installation of an annular pipe within the opening and unfolded around an outer surface of the annular pipe to seal the joint between the wall and the annular pipe and to methods of installing such a gasket within the wall and sealing the joint between the wall and the outer surface of the annular pipe.
In sewer lines, manholes are ordinarily installed at various intervals including locations where the sewer line changes elevation or direction. Manholes are typically formed in molds from a settable material such as concrete. The mold may form one or more annular openings in the manhole in which sewer pipes are positioned to lie adjacent a wall of the manhole defining that particular opening. The joint between the manhole wall and outer surface of the sewer pipe is sealed to prevent ground water from entering the manhole and to prevent contents of the manhole, such as sewage and water, from leaking out of the manhole. When ground water enters the manhole, it often brings in sediment which collects in the sewer over time. Such sediment causes clogs and inhibits the ability of the manhole to carry water. In addition, infiltration of ground water also increases the total volume of sewage flow through sewer lines which increases the required size of pipe needed as well as the expense of treatment of the total sewage flow. When the contents of the manhole leak, they can pollute the ground water.
Various types of gaskets for sealing joints between pipes and manholes are known. Often these gaskets are formed from an elastomeric material that is either inserted in an opening in the manhole and expanded via a ring or physically embedded in a portion of a wall adjacent the opening in the manhole. These gaskets typically provide at least one extending projection or sleeve (also called a boot) that surrounds and engages an outer wall or surface of a pipe extending through the gasket and the opening.
Expanded gaskets require rings that exert an outwardly, radially directed force on an inner surface of a gasket positioned within the opening to compress the gasket against a manhole wall defining the opening. These rings increase both material and labor installation costs associated with sealing the joint between the manhole wall and pipe. Material costs are increased because these rings are somewhat complicated corrosion-resistant metal structures that must be manually fabricated or are molded plastic structures that are made, at least in part, from high strength, expensive compositions. Labor costs are increased because installation and expansion of such rings to effect a seal requires maintaining proper alignment of the ring and use of equipment such as mechanical expansion units. In addition, seal failure will occur if the rings are improperly installed.
Embedded gaskets resolve the above-described problems associated with expanded gaskets. Embedded gaskets include those that are compressed between the manhole wall and outer wall or surface of the pipe as well as those that include sleeves or boots that are compression clamped around the outer wall or surface of the pipe. Embedded gaskets solve the expense problem associated with the manufacture and installation of expansion gaskets because, at most, only a relatively inexpensive clamp must be attached around the outside of the sleeve of the gasket to effect a seal. Embedded gaskets also allow a larger diameter of pipe to be inserted into an opening in a manhole than expanded gaskets because a separate ring is unnecessary. As is known, outside pipe diameter size can increase up to a certain point at which an expanded gasket can no longer be used for a particular sized manhole because the width of a wall defining an opening in the manhole will no longer be large enough to support the expansion ring. This means that a next, larger sized, more expensive manhole must be used for the larger diameter pipe.
A further advantage of compression embedded gaskets over expanded gaskets is that they can be set in the wall of the manhole defining the opening so that they must be released before being used. Releasably setting a gasket within the wall helps protect it against damage during shipment and handling. An advantage of sleeved embedded gaskets over compression embedded gaskets is that they can be less expensive because they can be formed from a thinner mass of elastomer. The same is not always true of compression embedded gaskets which often rely upon an extra mass of elastomer for compression. Another advantage of sleeved embedded gaskets is that they do not require as high a precision joint between the inside diameter of the manhole wall and the outside diameter of the pipe to effect a seal. Compression embedded gaskets only work within a small range of tolerances between these two diameters. If either of these diameters is outside the tolerance range, a compression embedded gasket will not properly seal. A further advantage of sleeved embedded gaskets is that they allow for a greater amount of lateral and vertical adjustment and deflection of an inserted pipe than do compression embedded gaskets. This means that greater amounts of pipe movement can occur while still maintaining a positive, fluid-tight seal. An embedded gasket that included a sleeve that is releasably secured to a manhole wall would be a welcome improvement. Such as gasket would be protected during shipping and handling while, at the same time, exploiting the advantages of sleeved embedded gaskets over compression embedded gaskets.
The opening defined by a wall of a manhole and a gasket embedded in the wall may be formed through the use of a mold and a settable material such as concrete. However, before the mold can be removed, sufficient time must pass to allow the settable material to cure or harden. Mass production thus requires several of these forms because of this curing time. This presents a problem because such molds are expensive to manufacture and often difficult to obtain on short notice. A less expensive method of embedding or casting a gasket within a wall defining an opening particularly suited for mass production or short notice would thus be a welcome improvement.
Non-precision joints between pipes, such as bell and spigot end pipes, are often sealed with a filler such as concrete and caulking. These fillers may allow ground water to enter the pipes or allow the contents of the pipes, such as sewage and water, to leak out. When ground water enters the pipes, it often brings in sediment which collects in the pipes. Such sediment can clog the pipes and inhibit their ability to carry away sewage and water. When the contents of the pipes leak, they can pollute ground water.
Sealing of precision joints between bell and spigot ends of pipes is typically achieved through the use of an elastomeric gasket between the joint. However, these precision joints may become out-of-tolerance over time as a result of dimensional changes of the pipe-making equipment during pipe manufacture or movement of one or more of the pipes due to, for example, settling of material underlying a pipe. Once the joints become out of tolerance, the above-described leakage and in-flow problems can occur.
A gasket that could be used in both non-precision and precision pipe joints and solved the above-described problems would be a welcome improvement. Accordingly, the present invention includes a gasket for sealing a joint between a wall defining an opening and an outer surface or wall of an annular member. The gasket of the present invention is embedded or cast within the wall defining the opening and includes a sleeve that can be folded adjacent the wall defining the opening and unfolded around the outer surface or wall of the annular member. The folded position helps protect the sleeve against damage during shipping and handling. The unfolded position provides a positive, substantially fluid-tight seal around an outer surface or wall of the annular member through only the use of clamp around a portion of the sleeve and annular member.
An embodiment of the gasket includes an annular body or base cast within and adjacent a wall of a manhole defining an opening in the manhole. The body or base is secured within the wall by one or more anchoring projections which, in preferred embodiments, include keylocks. In one preferred embodiment, the body or base is configured to have a length substantially equal to a width of the casting appliance (e.g., a fiberglass support plug). This helps prevent the settable material from which the wall and manhole are made from entering the gasket. An annular sleeve is coupled to the body and can be unfolded around an outer surface or wall of a pipe positioned to lie within the opening in the manhole. The body and sleeve, together, provide a positive, substantially fluid-tight seal of the joint between the manhole wall and outer surface or wall of the pipe. The sleeve includes first and second webs or skirts. The first web or skirt is connected to the second web or skirt by a hinge or fold and the second web or skirt is connected to the first web or skirt and body by hinges or folds. The hinges allow the first and second webs to be folded so that the first web lies adjacent the body in the folded position and the second web lies adjacent the first web in the folded position. The hinges or folds may be made from reduced portions or enervations in the sleeve and body.
An abutment member may be formed on a distal end of the first web that helps retain a clamp against lateral movement along the sleeve. In preferred embodiments, the abutment member includes an annular bead. A recess may be formed in the body or, alternatively, a portion of the manhole wall that captures the abutment member in the folded position to help retain the sleeve in that position. The abutment member must be manually removed from the recess to unfold the sleeve. The recess is configured to have dimensions that generally conform to the abutment member.
Another embodiment of the gasket of the present invention includes an annular body cast within and adjacent either an inside or outside wall of a bell end of an annular first pipe defining an opening in the first pipe. An annular sleeve or sheet is coupled to the body and can be unfolded around an outer surface or wall of an annular second pipe, a spigot end of which is positioned to lie within the opening in the bell end. The body and sleeve, together, provide a positive, substantially fluid-tight seal of a joint between the two pipes. The sleeve or sheet may also be folded adjacent the body to protect the sleeve from damage during shipping and handling. The sleeve or sheet may include a plurality of folds that allow it to be moved between these two positions.
An abutment member may be formed on a distal end of the sleeve that helps retain a clamp against lateral movement along the sleeve. In preferred embodiments, the abutment member includes an annular bead. A recess may be formed in the bell end of the first pipe that captures the abutment member or, alternatively, a portion of the sleeve in the folded position to help retain the sleeve in that position. The abutment member or sleeve must be manually released from the recess in order to unfold the sleeve. The recess is configured to have dimensions that generally conform to either the abutment member or that portion of the sleeve that is positioned to lie therein.
The body may include a receptacle in which the sleeve or sheet is positioned to lie when folded. One or more anchoring projections, such as keylocks, may be used to help secure the receptacle within the bell end of the first pipe.
The present invention also relates to a new method of casting a gasket of the present invention into a wall defining an opening in a manhole. The method includes the steps of cutting a first end of an annular member to have a first arc generally equivalent to a first arc of the inside diameter of the manhole and cutting a second end of the annular member to have a second arc generally equivalent to a second arc of an outside diameter of the manhole. The gasket is then positioned on an outer surface of the cut annular member. One or more spacers are next positioned on the outer surface of the cut annular member on both sides of the gasket. The cut annular member with gasket and spacers attached is then positioned within a mold used to form the wall of the manhole. Next, settable material is poured into the mold and cured so that the gasket is cast within the wall formed by the mold. Finally, the spacer, annular member, and mold are removed so that the gasket is positioned adjacent the wall of the manhole in a folded position.
The annular member may include a plastic pipe and the spacer may include a foam filler gasket made from materials such as foam water pipe insulation, rubber hose, and foam tape. The spacers may be formed a predetermined length to position the gasket generally in the center of the wall. In addition, the annular member may be cut a predetermined sufficient length to reduce bleed-by of the settable material during casting and curing.
The gasket of the present invention provides a method of sealing a joint between a wall defining an annular opening in a first member and an annular outer surface of a second member. The method includes the steps of forming an annular elastomeric gasket having a body portion, a radially directed anchoring projection, and a sleeve coupled to the body that can be moved between folded and unfolded positions. The formed gasket is positioned, with the sleeve folded, in an annular mold and the first member is cast from settable material poured in the mold to embed the anchoring projection in a wall of the formed first member. This positions the body of the gasket adjacent the wall. Next, the settable material is cured and the annular mold removed to provide an annular opening. The sleeve is then unfolded in an outwardly directed sealing position away from the body and a second member is inserted through the sleeve to form a positive, substantially fluid-tight seal between the wall of the first member and the outer surface of the second member.
The sleeve may be cast in the wall so that it is necessary to release it prior to unfolding the sleeve. The forming step may further include the steps of extruding the gasket in a generally straight condition, cutting the gasket at a length of approximately an outside diameter of the second member and joining the first and second ends of the cut gasket, via such conventional means as vulcanization, to form an annular shape. The body may be further formed so that it has a length substantially equal to a width of the adjacent wall of the first member.
The first annular member may be a manhole or, alternatively, a bell end of a pipe. When the first member includes a bell end of pipe, the body may include a receptacle to which the sleeve is coupled and in which the sleeve is positioned to lie in the folded position.
A further embodiment of the present invention involves the use of folded gaskets in conjunction with annular supports. According to this embodiment, a folded gasket is stretched over an annular support. This causes the folded gasket to be compressed radially outward so that a pipe can be inserted into the annular support. The annular support includes a helical strip which can be stripped apart to remove the annular support from within the folded gasket. After the pipe is inserted in the annular support, the annular support is stripped out from between the compressed, folded annular gasket and the pipe. Removal of the annular support causes the folded gasket to press against the pipe and thereby form a seal. According to more preferred embodiments, removal of the annular support causes the folded annular gasket to invert. The inverted part of the annular gasket can be clamped to the pipe and function as a boot or sleeve to provide a fluid tight seal.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.